Single contact actuator assembly

ABSTRACT

A pressure sensitive contact actuator comprises an elastomeric housing having a pair of electrical conductor contact plates disposed within the housing in a spaced apart parallel relationship. The plates are held in place by integrally formed elastomeric cantilever ledges that also act as guideways in the assembly of the actuator. Lead wires are connected to the plates through an end plug that seals off the interior of the housing from the elements. Depression of the housing via pressure activates the actuator by close-circuiting the parallel plates.

United States Patent [191 Ramsey et al.

[ Feb. 18, 1975 SINGLE CONTACT ACTUATOR ASSEMBLY [75] Inventors: Ira E. Ramsey; Byron L. Fishbaugh,

both of St. Marys, Ohio [73] Assignee: The Goodyear Tire & Rubber Company, Akron, Ohio [22] Filed: Dec. 10, 1973 [21] Appl. No.: 423,038

[52] U.S. Cl. 200/86 R, 340/272 [51] Int. Cl. HOlh 13/16 [58] Field of Search 200/86 R, 85 R; 340/272,

[56] References Cited UNITED STATES PATENTS 2,823,279 2/1958 Schulenburg 200/86 R Primary Examiner-David Smith, Jr. Attorney, Agent, or Firm-F. W. Brunner; L. A. Germain [5 7] ABSTRACT 12 Claims, 10 Drawing Figures PATENIEDFEBI 8W5 3.867. 595

FIE-1 4A FIEZ SINGLE CONTACT ACTUATOR ASSEMBLY BACKGROUND OF THE INVENTION Contact actuators of the type described are finding increased use in automated highway tollgate operations. In this type application it is desired to count the number of vehicle axles passing through the gate and to do so requires that a plurality of switches be embedded in the roadway which are actuated by the pressure of the passing vehicle wheels through the gate. To accomplish this function, the switch actuators must be capable of withstanding a wide range of pressures provided by various type vehicles. In addition, and because of their placement within the roadbed, the switch actuators must be completely sealed from the elements, trouble free, and exhibit a life that warrants their use in this type heavy-duty application. Furthermore, the switch actuators must be easily installed, interchangeable and easily maintained. FIG. 1 illustrates a switch actuator according to the prior art wherein a pair of parallel contact plates 12 and 14 are molded or otherwise adhesively secured to respective upper and lower portions of the actuator housing. There are many and various ways that the switches of the prior art are made and all involve attempts to maintain accurate spacing between the two parallel contact plates. One such method is described in U.S. Pat. No. 3,395,209 to G. R. Millard. These attempts at assembling the contact actuator through a molding operation suffer from drawbacks which include flash material filling the space between the metal plates, adhesion failures of the plates, and distortion of the contact plates during the molding operation. Furthermore, the connecting wires to the plates become distorted and may be shorted out rendering the actuator no longer functional. Once the molding operation is complete, there is no way of determining that the actuator is functional except through testing each individual unit. Because the contact plates are assembled in the molding operation, the contact actuators of the prior art require a substantial amount of labor and consume much time in assembly limiting the manufacturers productive capacity and incurring substantial cost in production.

SUMMARY OF THE INVENTION The invention generally relates to electrical switches and more specifically to an improved contact actuator that is assembled without resort to the complex molding operations of the prior art.

In this respect, it is an object of the invention to provide a contact actuator that is fool-proof in assembly, easily installed, interchangeable, and economically maintained.

It is a further object of this invention to provide a contact actuator that may be adapted to many single contact applications covering a wide range of activating forces.

Another object is to provide a weather and moistureproof assembly adapted for harsh environmental applications.

These objects and other objects and advantages which will become more evident from the detailed description that follows are provided in a unique contact actuator comprising an elastomeric housing defining an inner chamber having an open end, said housing having integrally formed cantilever-type ledges protruding into the chamber for the support of a pair of identically shaped conductor plates. The plates are substantially U-shaped with lateral edge tabs that are slidably received by the cantilever ledges and supported thereby in spaced apart, parallel, and open-circuited relationship. An elastomeric plug seals the open end of the chamber and provides access to the conductor plates for connection to an electrical circuit.

DESCRIPTION OF THE DRAWINGS The features and advantages of the invention will be better understood from a consideration of the description that follows taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is an elevational end view, in section, showing a contact actuator of the prior art;

FIG. 2 is an elevational end view, in section, showing the contact actuator of the present invention;

FIG. 3 is a top plan view, in section, taken on line 33 of FIG. 2;

FIG. 4 is a side elevational view, in section, taken on line 44 of FIG. 2;

FIG. 5 is a bottom plan view of the actuator end plug;

FIG. 6 is a side elevational view of the end plug;

FIG. 7 is an end elevational view of the end plug;

FIG. 8 is an enlarged sectional view taken through an access hole in the end plug;

FIG. 9 is a top plan view of a contact plate; and

FIG. 10 is a side elevational view of the contact plate of FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION In the drawing, a contact actuator assembly 18 is shown and comprises a molded elastomeric housing member 20, contact plates 30, and a molded elastomeric end plug 40.

The contact plates 30 are identical and may be stamped from any electrically conductive material suit able for handling the current requirements in a particular application. For a vehicle actuated switch the preferred plate material is a 22-gauge, type 301, stainless steel, half hardened temper. As illustrated in FIGS. 2, 9, and 10, the contact plates are formed with indented edge tabs 32 and 34 along the lateral edges of the plate. The tabs may extend the full length of the plate but to insure adequate flexibility they are preferably intermittent to provide support for desired locations along the length of the plate. Of course, two tabs will suffice for a shorter contact plate while more than three may be preferred on a longer plate. In any case, the number of tabs and their location will depend upon the gauge and material selected for the plates to provide adequate flexibility in operation. At one end of the plate and in the same plane as the main body or contact portion 30a, is a tab extension 36 to provide a suitable connection to an external circuit via wires 50, more clearly shown in FIGS. 3 and 4.

The actuator housing 20 is an injection, transfer, or compression molded elastomeric member defining an inner chamber and uniquely designed to accept the contact plates 30 in juxtaposed parallel relationship within the chamber. To accomplish this, cantilever ledges 22 are molded to extend into the housing chamber 24 and along both sides of the chamber such that symmetry exists between top and bottom halves of the housing if it were bisected along its horizontal centerline 33. The ledges 22 are shaped to receive the tabs 32 and 34 of a contact plate 30 to provide cantilevered suspension of the plate in its horizontal position within the housing chamber 24. Also extending into the housing chamber are pressure bearing surfaces 26 that mate with the body portion 30a of a contact plate when it is in position Within the housing. While one end is sealed in molding of the member 20, the other end is left open to facilitate insertion of the contact plates upon assembly. The open end of the housing chamber 24 is shaped to receive the end plug 40 in closely fitted and sealing engagement.

The end plug 40 is illustrated in FIGS. 5, 6, and 7 and comprises an injection, transfer, or compression molded elastomeric member of a generally rectangular configuration that fits snugly into the open end of the housing member 20. To facilitate inserting of the plug into the housing chamber 24, the sidewalls are slightly tapered, and, to provide a tight fit and sealing engagement with the chamber walls, single or multiple, integrally formed ribs 42 are located around the crown portion of the plug. Access to the contact plate connector tabs 36 is made through a pair of formed holes 44 that are located in the plug body and in alignment with the tab positions so that lead wires may be inserted through the plug and soldered or otherwise attached to the plate connector tabs 36.

To facilitate inserting of the lead wires 50 through the plug, the holes 44 have tapered entrance areas 46 and the body or crown portion of the plug is not as thick in the area 40a around the holes 44. The two legs 40b, that are formed by the cutout area 400, provide additional cushioning in the area of the lead wire connections and also act as keepers to limit horizontal movement of the contact plates when fully inserted and in butted relationship with the ends of the ledges 22 as clearly shown in FIG. 3. While the ribs 42 around the crown of the plug provide sealing of the plug in the housing chamber, a like plurality of integrally formed flexible protrusions or ribs 48 are located within the hole cavities 44 to provide a sealing engagement with the lead wire insulation as it is pulled through the hole. As clearly illustrated in FIG. 8, the ribs 48 have a sealing taper such as to facilitate insertion and to resist extraction of the lead wires from the plug. An alternate plug structure (not shown) incorporates the lead wires and plug in an integrally molded unit, thus eliminating the possibility of inadequate sealing.

Assembly of the actuator is fast and fool-proof. The contact plates 30, while being identical, can only be inserted in the actuator housing chamber 24 in a single position. As shown in FIG. 2, the plate edge tabs 32 and 34 are slidably received by the cantilever ledges 22 on either side of the housing chamber. With one actuator plate inserted in the chamber the other must be turned over in opposing position in order to be inserted. Once inserted in the housing, the plates are held in juxtaposed parallel relation along their length by the tab/- ledge relationship. In this position, the plates are opencircuited when connected to an outside electrical circuit. Also, since the contact plates are identical in all respects, turning the one over, positions the connector tab 36 at the opposite side of the housing from the tab 36 for the opposing contact plate. This feature insures against accidental short-circuiting of the lead-wire connections when the plug 40 is inserted in the housing chamber 24.

In production, the actuator housing 20, end plug 40, and plates 30 are made separately and brought together for assembly. To assemble, short lengths of lead wire 50 are pulled through the plug holes 44 and soldered or crimped onto the contact plate connector tabs 36. The plates are next inserted into the housing cavity using the ledges 22 as guideways, and the end plug is inserted to seal the chamber. Prior to inserting the plug, an adhesive may be applied to it, to provide additional security against moisture leaks and to keep the plug from working its way out of the housing when it is flexed by the application of pressure upon its top surface. In this respect, the plug ribs 42 may be eliminated since the adhesive provides sufficient sealing.

While the invention is described with respect to a heavy-duty and vehicle actuated application, it is considered within the scope of the appended claims to apply it to less harsh environments. For example, the invention may be applied to human actuated dooropening devices and the like by merely compounding the elastomeric material so that less pressure need be applied to close-circuit the contact plates. Also, other materials may be selected for the contact plates to provide increased flexibility.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed is:

1. A contact actuator providing an on/off function in an electrical circuit, the actuator comprising:

A. an elastomeric housing member defining a chamber having an open end, said housing member having a pair of integrally formed cantilever ledges on each of opposing sides of the chamber, protruding into the chamber, and extending at least the partial length thereof;

B. a pair of U-shaped conductor plates juxtaposed within the chamber in opposed parallel position, said plates having tab extensions along the lateral edges thereof, the inner portion of the U-shape being in abutting relationship with the housing member while the outer portion provides a contact surface for close circuiting the actuator, said plates slidably received along their lateral edges by at least one pair of opposing cantilever ledges and constrained within the chamber by their relationship with the ledges; and

C. an elastomeric plug adapted to fit securely within the open end of the housing chamber to seal the chamber, said plug providing access to the conductor plates for connection to the electrical circuit.

2. The actuator as defined in claim 1, wherein the conductor plates comprise a half-hardened temper, type 301, 22-gauge stainless steel.

3. The actuator as defined in claim I, wherein the plug is in a substantially U-shaped configuration with the leg portions being tapered to facilitate insertion into the open end of the housing chamber and upon full insertion are in abutting relationship with the ends of respective conductor plates.

4. The actuator as defined in claim 3, wherein the plug has at least oneintegrally formed flexible peripheral rib to provide a sealing engagement within the housing chamber.

5. The actuator as defined in claim 3, wherein the plug is adhesively secured within the housing chamber.

6. The actuator as defined in claim 5, wherein a pair of formed holes are provided in the plug for access to the chamber and a pair of lead wires are fitted each through a respective access hole and connected to respective conductor plates within the housing chamber.

7. The actuator as defined in claim 6, wherein the access holes in the plug are horizontally aligned to provide separation between lead-wire/conductor-plate connections and integrally formed radial ribs protrude into the access holes to provide sealing engagement with the lead wires, said ribs being tapered to resist extraction of the wires from the plug.

8. The actuator as defined in claim 1, wherein a pair of lead wires are integrally formed within the plug such that one end of each may be connected to respective conductor plates while the opposite ends may be connected to the electrical circuit.

9. A single contact actuator adapted to provide an on-off function in an electrical circuit, the actuator comprising:

A. an elongated, substantially rectangular, elastomeric housing defining inner and outer interconnected chambers, the inner chamber having a pair of integrally formed cantilever type ledges on each of opposing chamber walls and extending the length thereof, the outer chamber being open at one end;

B. a pair of U-shaped electrical contact plates in spaced apart parallel position within the inner housing chamber, said plates having lateral edge tabs adapted to be received by the ledges on opposing chamber walls and the housing member has bearing surfaces protruding into the chamber to engage the inner portion of the plates such that the outer portion of the U-shape provides contact surfaces in face opposed position, each plate being slidably received and retained in position within the chamber by a pair of ledges such that a deflection of the housing initiates close-circuiting of the contact plates; and

C. an elastomeric plug adapted to fit securely within the open end of the outer chamber to seal the chamber, said plug having disposed therein, a pair of electrical lead wires for connection to respective contact plates and the electrical circuit.

10. The actuator according to claim 9, wherein the plug and lead wires are an integrally formed unit.

11. The actuator according to claim 9, wherein the plug is adhesively secured within the outer housing chamber.

12. The actuator according to claim 9, wherein the plug is force fitted into the outer chamber and is held in position by at least one integrally formed peripheral rib. 

1. A contact actuator providing an on/off function in an electrical circuit, the actuator comprising: A. an elastomeric housing member defining a chamber having an open end, said housing member having a pair of integrally formed cantilever ledges on each of opposing sides of the chamber, protruding into the chamber, and extending at least the partial length thereof; B. a pair of U-shaped conductor plates juxtaposed within the chamber in opposed parallel position, said plates having tab extensions along the lateral edges thereof, the inner portion of the U-shape being in abutting relationship with the housing member while the outer portion provides a contact surface for close circuiting the actuator, said plates slidably received along their lateral edges by at least one pair of opposing cantilever ledges and constrained within the chamber by their relationship with the ledges; and C. an elastomeric plug adapted to fit securely within the open end of the housing chamber to seal the chamber, said plug providing access to the conductor plates for connection to the electrical circuit.
 2. The actuator as defined in claim 1, wherein the conductor plates comprise a half-hardened temper, type 301, 22-gauge stainless steel.
 3. The actuator as defined in claim 1, wherein the plug is in a substantially U-shaped configuration with the leg portions being tapered to facilitate insertion into the open end of the housing chamber and upon full insertion are in abutting relationship with the ends of respective conductor plates.
 4. The actuator as defined in claim 3, wherein the plug has at least one integrally formed flexible peripheral rib to provide a sealing engagement within the housing chamber.
 5. The actuator as defined in claim 3, wherein the plug is adhesively secured within the housing chamber.
 6. The actuator as defined in claim 5, wherein a pair of formed holes are provided in the plug for access to the chamber and a pair of lead wires are fitted each through a respective access hole and connected to respective conductor plates within the housing chamber.
 7. The actuator as defined in claim 6, wherein the access holes in the plug are horizontally aligned to provide separation between lead-wire/conductor-plate connections and integrally formed radial ribs protrude into the access holes to provide sealing engagement with the lead wires, said ribs being tapered to resist extraction of the wires from the plug.
 8. The actuator as defined in claim 1, wherein a pair of lead wires are integrally formed within the plug such that one end of each may be connected to respective conductor plates while the opposite ends may be connected to the electrical circuit.
 9. A single contact actuator adapted to provide an on-off function in an electrical circuit, the actuator comprising: A. an elongated, substantially rectangular, elastomeric housing defining inner and outer interconnected chambers, the inner chamber having a pair of integrally formed cantilever type ledges on each of opposing chamber walls and extending the length thereof, the outer chamber being open at one end; B. a pair of U-shaped electrical contact plates in spaced apart parallel position within the inner housing chamber, said plates havinG lateral edge tabs adapted to be received by the ledges on opposing chamber walls and the housing member has bearing surfaces protruding into the chamber to engage the inner portion of the plates such that the outer portion of the U-shape provides contact surfaces in face opposed position, each plate being slidably received and retained in position within the chamber by a pair of ledges such that a deflection of the housing initiates close-circuiting of the contact plates; and C. an elastomeric plug adapted to fit securely within the open end of the outer chamber to seal the chamber, said plug having disposed therein, a pair of electrical lead wires for connection to respective contact plates and the electrical circuit.
 10. The actuator according to claim 9, wherein the plug and lead wires are an integrally formed unit.
 11. The actuator according to claim 9, wherein the plug is adhesively secured within the outer housing chamber.
 12. The actuator according to claim 9, wherein the plug is force fitted into the outer chamber and is held in position by at least one integrally formed peripheral rib. 